Abstract:
Evaluating the risk posed by a contaminated site involves assessing hazards, receptors and exposure pathways. Since risk exists only
when all three of these components are present, it is advantageous to use a multiplicative model as the REA rather than a summative
model for assessing risk potential. Hazard (contaminant), receptor and exposure pathway scores are developed under a
methodological framework that reduces opportunities for judgmental bias. The model was therefore used to categorize and prioritize
the visited sites and recommend the sites which require immediate detailed action. The purpose of the site assessments was to identify
the existence, source, nature, and extent of POPs contamination of Menengai Crater, Kitengela and Wajir dump sites. From the
residual chemical analysis of samples collected, the sites are heavily contaminated with residual POPs (lindane, aldrin, dieldrin, 2,4-
DDE, 2,4-DDT, and endrin) and other residual pyrethroids (bifenthrin, cypermethrin, pendimethalin, and permethrin) beyond the set
International Standards for such residual pollutants in the environment (USAEPA, Dutch Intervention POPs Levels)(< 0.05 mg/Kg).
Menengai Crater 1, Kitengela and Wajir LMD indicated quite high levels of the POPs. The levels of POPs recorded in the analysis
are indicative of potential contamination of humans and animals and thus posing a great environmental threat. The pollutants are able
to pollute surface and ground water sources, contaminate surface soil both on site and away through long range dust transportation.
The analysis of REA questionnaire indicated that Wajir LMD site was the most at risk followed by Menengai Crater Dump Site 1, and
Kitengela respectively. Wajir LMD was the most at risk site due to the proximity and easy access to the site by human beings and thus
poses a great health threat to the local community members living and accessing the site. There was strong evidence of both horizontal
and vertical POPs contamination in all sites. The proximity of receptors such as homesteads and drinking water sources (at Wajir
LMD and Kitengela) to the contaminated sites, strongly indicate that the sites are potential human hazard and detailed investigations
should be put in place to ascertain the extent of contamination. The study proved with great certainty that the visited sites are heavily
contaminated with POPs and measures to reclaim and remediate the sites to avoid future human health and environment catastrophe
should be put in place.
